Martin O'Neill believes he should have been given more time to haul Sunderland clear of the relegation zone because of his achievements last season, when he claimed the club "was pretty much on its knees" and heading for the Championship until he replaced Steve Bruce.

Speaking for the first time since his sacking last Saturday night, O'Neill said that he was "pretty disappointed and frustrated" after he became the fifth Premier League manager to lose his job this season. Ellis Short, Sunderland's owner, called time on O'Neill's 15-month reign after the 1-0 home defeat by Manchester United, which extended the club's run without a victory to eight games, leaving them only one point above the relegation zone ahead of a demanding run of fixtures, starting with tomorrow's trip to Chelsea.

O'Neill, however, felt that he deserved better. He referred to his track record as a manager and pointed in particular to his impact at Sunderland last season, when he inherited a team 16th in the table with 11 points from 13 games. Sunderland went on to finish in 13th place.

"I thought with the experience that I've had over the years, and also perhaps just coming into the football club, at the time when the club was pretty well on its knees, and I believe I saved the club from relegation last year and I thought that opportunity should still have been afforded to me," O'Neill told BBC Radio 5 Live in a preview of today's Football Focus.

The 61-year-old said he was disappointed, rather than shocked, to learn he was being dismissed. "I'm in the business now where I think very little shocks you about professional football, particularly in the last 10 years. I think you can nearly lose your job in management if your tie doesn't fit your suit," said O'Neill, who suggested he is keen to return to the dugout.

A couple of weeks before he was sacked, O'Neill had said that Sunderland "lack real true ability in the team", which felt like a damaging comment to make about a side that was sliding towards the relegation zone. O'Neill, though, believes he was merely telling the truth. "I don't think it's a major criticism, it's there's for all to see. It's actually a fact."